Immunopotentiating of mucosal and systemic antibody responses in mice by intranasal immunization with HLT-combined influenza virosomal vaccine

The mucosal vaccination strategy against influenza has been investigated by using influenza virosomal vaccine (IRIV) combined with two different adjuv ants: the procholeragenoid (PCG) and the Escherichia coli heat labile toxin (HLT). A comparative study has been carried out on mice administered intra nasally with these different formulations of influenza vaccine. PCG appears less effective than HLT in inducing an IgG response, but both the adjuvant s elicit mucosal adjuvant activity inducing s-IgA. in the upper respiratory tract. On the contrary, only HLT when administered intranasally to mice wi th influenza virosomes stimulates the production of s-IgA in the lower resp iratory tract thereby providing a better protection against primary infecti on of the respiratory system. Both HLT and PCG enhance the production of IF N-gamma in the respiratory tract, nevertheless HLT appears more efficacious as a mucosal adjuvant, (C) 2000 Elsevier Science Ltd. All rights reserved.